If we tease the creature, we see welling up from the bottom of these several little craters an opalescent liquid, which runs and spreads all over the larva. It has a strong smell of bitter almonds, or rather of nitrobenzene, commonly known as essence of mirbane, a powerful and most repulsive smell. The discharge of this substance is a means of defence. We have only to tickle the insect with a straw or to grip one of its legs with the tweezers and the eighteen scent-bottles at once begin to work. Whoso handles the grub will find his fingers stink and will throw away the noisome perfumer in disgust. If the Chrysomela-larva’s object in placing nine pairs of nitrobenzene-stills on its back was to repel man, it has, I admit, thoroughly succeeded. But man is the least of its enemies. Far more formidable is the Odynerus, who seizes the scented creature by the skin of the neck and, despite its sprays of perfume, dispatches it with a few stings. This was the bandit against whom, above all, it should have defended itself; and the poor grub has not been happily inspired in this respect. Considering the huntress’ exclusive taste for this sort of game, we must presume that the Chrysomela’s drug-shop possesses a delicious aroma in the Odynerus’ opinion. The defensive secretion becomes a deadly bait. Even so with other means of protection: each advantage invariably has some corresponding disadvantage. I have read, I forget where, the story of certain South-American Butterflies, some of whom tasted bitter, others not. The first were respected by the birds because of their bitterness; the second were eagerly swallowed. What did the persecuted insects do? Unable to acquire the disagreeable flavour of the bitter ones, they at least imitated their shape and their costume. And the birds were taken in by the fraud. This was put forward as a striking proof of evolution in view of the struggle for life. I am repeating the story more or less correctly, as it lingers vaguely in my memory, for I have never attached more importance than they deserve to pretty inventions of this kind. Is it really certain that the pungent Butterflies escaped destruction because of their taste? Might there not be, among the birds, a few passionate lovers of bitters, to whom the defensive flavour was, on the contrary, an added lure? My two acres of pebbles tell me nothing of things Brazilian; nevertheless I learn within their four walls that a grub of detestable flavour, of the most repulsive aroma, has, like the others, its appointed consumers and very zealous consumers at that. If the struggle for life made it acquire its scent-bottles, then the struggle for life is a fool: it should have left the creature without them. In this way the enemy most to be feared, the Odynerus, who is attracted by the smell, would have been avoided.